Fluid dispensers of various types are known. In particular, for dispensing of cleaning products such as soaps, there are a wide variety of manually or automatically actuated pumps that dispense a given quantity of the product into a user's hand.
Consumer products may include a dispensing outlet as part of the package, actuated by a user pressing down the top of the package. Such packages use a dip tube extending below the level of the liquid and a piston pump that aspirates the liquid and dispenses it downwards through an outlet spout.
Commercial dispensers frequently use inverted disposable containers that can be placed in dispensing devices, affixed to walls of washrooms or the like. The pump may be integrated as part of the disposable container or may be part of the permanent dispensing device or both. Such devices are generally more robust and, as they are affixed to the wall, greater freedom is available in the direction and amount of force that is required for actuation. Such devices may also use sensors that identify the location of a user's hand and cause a unit dose of the product to be dispensed. This avoids user contact with the device and the associated cross-contamination. It also prevents incorrect operation that can lead to damage and premature ageing of the dispensing mechanism.
A characteristic of inverted dispensers is the need to prevent leakage. Since the pump outlet is located below the container, gravity will act to cause the product to escape if there is any leakage through the pump. This is particularly the case for relatively volatile products such as alcohol based solutions. Achieving leak free operation is often associated with relatively complex and expensive pumps. For the convenience of replacing empty disposable containers however, at least part of the pump is generally also disposable and must be economical to produce. There is therefore a need for a pump that is reliable and drip free, yet simple and economical to produce.
One disposable dispensing system that uses a pump to dispense a unit dose of fluid from an inverted collapsible container has been described in WO2011/133085. The pump, which in this case is described for dispensing foam includes a piston element and a cylinder that slide, one within the other to dispense the foam. Valves (not shown) are present to control inflow and outflow. The pump is a relatively complex item to manufacture and assemble due to the large number of components, all of which must be compatible with the different fluids that may be pumped. Since the pump is disposable, the presence of multiple components of different materials is also of concern. Additionally, although the sliding seal operates in a satisfactory manner, it remains a location where attention must be paid to contamination and leakage. It would be desirable to provide a pump that could be an alternative to existing axially operating dispensers.